Decontamination of Sulfur Contaminants from a Vessel

ABSTRACT

A method for treating sulfur contaminants is provided. The method comprises introducing a methylmorpholine-N-oxide solution to a vessel, wherein the vessel comprises a water layer and a gas layer, wherein the water layer and the gas layer comprise the hydrogen sulfide; introducing methylmorpholine-N-oxide into the water layer; and treating the water layer by allowing the methylmorpholine-N-oxide to react with the hydrogen sulfide.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a continuation application of U.S. patent application Ser. No.16/107535 filed on Aug. 21, 2018 which is a continuation application ofU.S. Pat. No. 10,052,583 issued on Aug. 21, 2018 and filed on Sep. 21,2015, titled “Decontamination of Sulfur Contaminants from a Vessel,” theentire disclosure of which is herein incorporated by reference.

BACKGROUND OF THE INVENTION Field of the Invention

Methods and systems for the decontamination of sulfur contaminates fromvessels containing sulfur contaminants are provided. Specifically,methods and systems of using methylmorpholine-N-oxide to remove sulfurcontaminants from vessels comprising water and/or gas contaminated withsulfur contaminants are provided.

BACKGROUND OF THE INVENTION

Refineries and petrochemical plants are commonly contaminated withsulfur contaminants such as H₂S. These sulfur contaminants may typicallybe mitigated or removed as part of decontamination procedures, forinstance, prior to vessel (e.g., large storage tanks) entry byindividuals. A conventional approach to decontamination is to usehydrogen sulfide scavengers (e.g., liquid scavengers) such as triazine,acrolein, or formaldehyde. Such scavengers may rely on non-oxidativecomplexation and may be an economical approach for H₂S decontamination.Liquid scavengers may tie up H₂S as water-soluble compounds that may bedischarged to wastewater treatment facilities. However, such scavengershave drawbacks. For instance, some of the reaction products may not bewater-soluble, and some of the treatment chemicals may have associatedtoxicity or environmental restrictions in certain locations. Inaddition, some sulfur contaminants may only be removed by specificscavengers, for example, typically only acrolein may neutralizepyrophoric iron sulfides. Additionally, triazine treatments may raisethe pH of effluent streams and as a result, may promote the formation ofscales on metal surfaces. Formaldehyde reactions with H₂S typicallyproduce water insoluble products. Further, acrolein benefits may betempered by its toxicity.

Other methods have been developed and demonstrated to be effective atoxidizing and eliminating sulfur contaminants. Such methods includeusing permanganate (e.g., potassium permanganate), persulfate, sodiumnitrite, ozone, hypochlorite, adducts of peroxide such as perborates andpercarbonates, and long-chain amine oxides. The oxidizing chemicals mayirreversibly convert sulfur contaminants (e.g., H₂S) to harmless watersoluble forms of sulfur, which may be compatible with effluentdischarge. Each of these oxidizing compounds (i.e., oxidizing chemicals)have certain drawbacks. Hypochlorite may form dangerous chlorinecompounds. Ozone and permanganate may involve field mixing. Permanganatedecontaminations may be further complicated by large amounts of reactionsolids that are typically processed at additional cost. Percarbonates,as with permanganate, may also be exothermic in their reaction, whichmay be particularly dangerous if hydrocarbon vapors are present.Further, treatments using strong oxidizers (i.e., permanganate,percarbonate, persulfate) are typically accomplished in small sequentialbatches outside the storage vessel in order to control the associatedexotherm. As a result, these treatments may involve considerable timeand therefore cost. The strong oxidizers may also be corrosive.Moreover, these compounds may also react violently with hydrocarboncomponents that may be present in sour sludge. For example, the strongoxidizers may be non-selective in their reaction and may react with manyof the hydrocarbon components that may exist in sludge which may becontained in storage vessels. As a result, these treatments may bepreformed in small sequential batches outside the vessel, which mayincrease operation time and expenditures.

Mild oxidizers such as amine oxides and nitrites may be effective atoxidizing sulfur contaminants to harmless forms of sulfur while havinglimited or having no effect on hydrocarbons, unlike strong oxidizers.Additionally, mild oxidizers may be added directly to a vessel as theirassociated reactions may be non-exothermic. However, mild oxidizers alsohave drawbacks. For instance, typical long-chain amine oxides may posefoaming issues due to their surfactant nature. These amine oxides mayalso have limited efficiency for large amounts of H₂S, since they aretypically diluted in water to prevent gel formation. Nitrites may alsohave drawbacks, as their reaction with hydrogen sulfide producesammonia. As a result, the nitrite oxidation reaction may be accompaniedby a rise in pH, which at some point may cease the oxidation before itis complete.

Consequently, there is a need for improved methods and systems fordecontaminating vessels contaminated with sulfur contaminants.

BRIEF SUMMARY OF SOME OF THE PREFERRED EMBODIMENTS

These and other needs in the art are addressed in one embodiment by amethod for removing hydrogen sulfide. The method may compriseintroducing a methylmorpholine-N-oxide solution to a vessel, wherein thevessel comprises a water layer and a gas layer, wherein the water layerand the gas layer comprise the hydrogen sulfide; introducingmethylmorpholine-N-oxide into the water layer; and treating the waterlayer by allowing the methylmorpholine-N-oxide to react with thehydrogen sulfide.

These and other needs in the art are addressed in another embodiment bya method for removing hydrogen sulfide. The method may compriseintroducing a methylmorpholine-N-oxide solution to a vessel, wherein thevessel comprises a water layer and a gas layer, wherein the water layerand the gas layer comprise the hydrogen sulfide; introducingmethylmorpholine-N-oxide into the gas layer; and treating the gas layerby allowing the methylmorpholine-N-oxide to react with the hydrogensulfide.

The foregoing has outlined rather broadly the features and technicaladvantages of the present invention in order that the detaileddescription of the invention that follows may be better understood.Additional features and advantages of the invention will be describedhereinafter that form the subject of the claims of the invention. Itshould be appreciated by those skilled in the art that the conceptionand the specific embodiments disclosed may be readily utilized as abasis for modifying or designing other embodiments for carrying out thesame purposes of the present invention. It should also be realized bythose skilled in the art that such equivalent embodiments do not departfrom the spirit and scope of the invention as set forth in the appendedclaims.

BRIEF DESCRIPTION OF THE DRAWINGS

For a detailed description of the preferred embodiments, reference willnow be made to the accompanying drawings in which:

FIG. 1 illustrates an embodiment of a methylmorpholine-N-oxide watertreatment method;

FIG. 2 illustrates another embodiment of a methylmorpholine-N-oxidewater treatment method;

FIG. 3 illustrates reaction time versus temperature of a reactionmethylmorpholine-N-oxide and H₂S; and

FIG. 4 illustrates an embodiment of a methylmorpholine-N-oxide watertreatment method having a heat exchanger and re-circulation.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 illustrates an embodiment of methylmorpholine-N-oxide watertreatment method 5. In an embodiment, methylmorpholine-N-oxide watertreatment method 5 treats a vessel comprising water and gas contaminatedwith sulfur contaminants by decontaminating the water and gas byremoving a portion or all of the sulfur contaminants from the water andthe gas.

In embodiments as shown in FIG. 1, contaminated water (e.g., sour water)and/or contaminated gas (e.g., sour gas) may be disposed within vessel10. As used herein, “contaminated” refers to water and/or gascontaminated with sulfur contaminants. It is to be understood that“contaminated” does not exclude water and gas contaminated with othertypes of contaminants in addition to or other than the sulfurcontaminants. Vessel 10 may include any type of vessel that may containwater and gas. In an embodiment, vessel 10 is a tank. In someembodiments, vessel 10 comprises a water layer 15 and a gas layer 20. Inembodiments, one or both of the water layer 15 and the gas layer 20 arecontaminated with sulfur contaminants. Without limitation, examples ofsulfur contaminants include hydrogen sulfide, iron sulfides, or anycombinations thereof. In an embodiment, the sulfur contaminant compriseshydrogen sulfide. In some embodiments, the iron sulfides comprisespyrophoric iron sulfides. The pyrophoric iron sulfides may include anypyrophoric iron sulfides. In embodiments, the pyrophoric iron sulfidescomprise pyrite, troilite, marcasite, pyrrhotite, or any combinationthereof.

The water layer 15 and the gas layer 20 may be contaminated with thesulfur contaminants by any method of contamination. The sulfurcontaminants may be provided to the water layer 15 and the gas layer 20from any source. The sulfur contaminants may be present in the waterlayer 15 and the gas layer 20 at any concentration. Without limitation,the sulfur contaminants may be present in the water layer 15 and/or thegas layer 20 in an amount in a range including any of and between any ofabout 100 ppm to about 180,000 ppm. For example, the sulfur contaminantsmay be present in the water layer 15 and the gas layer 20 in an amountof about 100 ppm, about 500 ppm, about 1000 ppm, about 5000 ppm, about10,000 ppm, about 15,000 ppm, about 50,000 ppm, about 100,000 ppm, about150,000 ppm, about 180,000 ppm, or any ranges therebetween.

FIG. 1 shows an embodiment of a methylmorpholine-N-oxide water treatmentmethod 5 in which methylmorpholine-N-oxide 25 is introduced to vessel10. In the embodiment illustrated by FIG. 1, methylmorpholine-N-oxide 25is introduced to the water layer 15 disposed within vessel 10.Methylmorpholine-N-oxide 25 may be introduced to vessel 10 by anysuitable means. Without limitation, examples of such suitable meansinclude a drum pump, tank truck, and the like. Methylmorpholine-N-oxide25 may be introduced in any suitable form for removing the contaminantsfrom the contaminated water. In some embodiments,methylmorpholine-N-oxide 25 is in a methylmorpholine-N-oxide solutioncomprising the methylmorpholine-N-oxide 25 and water. Themethylmorpholine-N-oxide solution may have the methylmorpholine-N-oxide25 in any desired amount. In some embodiments, themethylmorpholine-N-oxide 25 may be in a very concentrated form in themethylmorpholine-N-oxide solution. Without being limited by theory, suchvery concentrated form may allow the methylmorpholine-N-oxide 25 to beapplied in small, efficient amounts. The concentrated form may includeany desirable concentration. In an embodiment, the concentration ofmethylmorpholine-N-oxide 25 in the water layer 15 is between about 0.01weight volume % and about 60 weight volume %, alternatively betweenabout 10 weight volume % and about 20 weight volume %, furtheralternatively between about 5 weight volume % and about 60 weight volume%, and alternatively between about 50 weight volume % and about 60weight volume %. In embodiments, the concentration ofmethylmorpholine-N-oxide 25 in the water layer 15 may be any individualweight volume % in the above ranges or any smaller range of weightvolume % that is included in the above ranges. In an embodiment, theconcentration of methylmorpholine-N-oxide 25 in the water layer 15 isbetween about 0.01 weight volume % and about 10 weight volume %. In anembodiment, the methylmorpholine-N-oxide 25 is a short-chain amineoxide. In embodiments, the methylmorpholine-N-oxide 25 has the molecularformula C₅H₁₁NO₂. In vessel 10, methylmorpholine-N-oxide 25 contacts thewater layer 15 comprising the sulfur contaminants. In some embodiments,methylmorpholine-N-oxide 25 is not heated before introduction to vessel10. In embodiments, the amount of methylmorpholine-N-oxide 25 added tovessel 10 provides a mole ratio of methylmorpholine-N-oxide: a sulfurcontaminant in the water layer 15 disposed within vessel 10 from about1.0 mole methylmorpholine-N-oxide: 1.0 mole of a sulfur contaminant toabout 3.0 mole methylmorpholine-N-oxide: 1.0 mole of a sulfurcontaminant, or any range or mole ratio therebetween.

In the embodiments shown in FIG. 1, steam 30 may also be added to vessel10. Steam 30 may be added to increase the temperature of the water layer15 and/or the gas layer 20 disposed within vessel 10. In someembodiments, steam 30 may be added to vessel 10 in amounts as desired.In some embodiments, steam 30 may be added in a continuous manner.Without limitation, steam 30 may be added to increase the temperature ofthe water layer 15 and/or the gas layer 20 to a temperature from about70° F. to about 250° F., alternatively, from about 75° F. to about 125°F., from about 120° F. to about 250° F., from about 150° F. to about235° F., or further alternatively, from about 200° F. to about 250° F.In embodiments, the temperature may be any individual temperature in theabove ranges or any smaller range of temperatures that is included inthe above ranges. Any suitable psig steam 30 may be used. Inembodiments, the steam 30 is 150 psig or less. In an embodiment, thesteam 30 is 50 psig. In an embodiment, the steam 30 is 150 psig.

With continued reference to FIG. 1, as the methylmorpholine-N-oxide 25reacts with and removes the sulfur contaminants in the water layer 15,the concentration gradient of the sulfur contaminants in the water layer15 may decrease, and the capacity of the water layer 15 to dissolve moreof the sulfur contaminants may be increased. Any sulfur contaminantsthat may have been present in the gas layer 20 or any sulfurcontaminants that may have evaported into the gas layer 20 after a heattransfer initiated by the application of the steam 30 may contact theinterface between the water layer 15 and the gas layer 20 and maycondense into the water layer 15. The rate at which the sulfurcontaminants condense into the water layer 15 may be determined by thetemperature, pressure, and the concentration gradient of the sulfurcontaminants in the water layer 15. The methylmorpholine-N-oxide 25 maythen act to remove the sulfur contaminants that have condensed into thewater layer 15 from the gas layer 20, thus decontaminating both thewater layer 15 and the gas layer 20. The rate of condensation may beadjusted by reducing the temperature of the system, increasing thepressure of the system, increasing the surface area of the interfacebetween the water layer 15 and the gas layer 20, or any other suitablemeans for condensing the sulfur contaminants into the water layer 15.

FIG. 2 illustrates another embodiment of methylmorpholine-N-oxide watertreatment method 5. As with FIG. 1, methylmorpholine-N-oxide watertreatment method 5 treats a vessel 10 comprising a water layer 15 and agas layer 20 contaminated with sulfur contaminants by decontaminatingthe water layer 15 and the gas layer 20 by removing a portion or all ofthe sulfur contaminants from the water layer 15 and the gas layer 20.However, FIG. 2 shows an embodiment of methylmorpholine-N-oxide watertreatment system 5 in which methylmorpholine-N-oxide 25 is introduced tovessel 10 in the gas layer 20. In the embodiment illustrated by FIG. 2,methylmorpholine-N-oxide 25 may be introduced to the gas layer 20disposed within vessel 10 by any suitable means. Without limitation,examples of such suitable means include a drum pump, tank truck, and thelike. As in FIG. 1, steam 30 may be added to vessel 10 to increase thetemperature of the gas layer 20. For the embodiment described by FIG. 2,the temperature of the gas layer 20 may be higher than the boiling pointof the methylmorpholine-N-oxide 25 so as to maintain themethylmorpholine-N-oxide in the gas phase. Specifically, the temperatureof the gas layer 20 may be above 234° F. In alternative embodiments,methylmorpholine-N-oxide 25 may be added with steam 30. Further,alternatively, if desired, the temperature of the gas layer 20 may bereduced to below the boiling point of the methylmorpholine-N-oxide 25,and the methylmorpholine-N-oxide 25 may condense into the water layer15. The methylmorpholine-N-oxide 25 may be introduced into the gas layer20 in any desired amount. In some embodiments, themethylmorpholine-N-oxide 25 may be in a very concentrated form in thegas layer 20. In an embodiment, the concentration ofmethylmorpholine-N-oxide 25 in the gas layer 20 is between about 0.01weight volume % and about 60 weight volume %, alternatively betweenabout 10 weight volume % and about 20 weight volume %, furtheralternatively between about 5 weight volume % and about 60 weight volume%, and alternatively between about 50 weight volume % and about 60weight volume %. In embodiments, the concentration ofmethylmorpholine-N-oxide 25 in the gas layer 20 may be any individualweight volume % in the above ranges or any smaller range of weightvolume % that is included in the above ranges. In an embodiment, theconcentration of methylmorpholine-N-oxide 25 in the gas layer 20 isbetween about 0.01 weight volume % and about 10 weight volume %. Inembodiments, the amount of methylmorpholine-N-oxide 25 added to vessel10 provides a mole ratio of methylmorpholine-N-oxide : a sulfurcontaminant in the gas layer 20 disposed within vessel 10 from about 1.0mole methylmorpholine-N-oxide: 1.0 mole of a sulfur contaminant to about3.0 mole methylmorpholine-N-oxide: 1.0 mole of a sulfur contaminant, orany range or mole ratio therebetween.

As with FIG. 1, steam 30 may also be added to vessel 10 in theembodiment illustrated by FIG. 2. Without limitation, steam 15 may beadded to increase the temperature of the water layer 15 and/or the gaslayer 20 to a temperature from about 70° F. to about 250° F.,alternatively, from about 75° F. to about 125° F., from about 120° F. toabout 250° F., from about 150° F. to about 235° F., or furtheralternatively, from about 200° F. to about 250° F. In embodiments, thetemperature may be any individual temperature in the above ranges or anysmaller range of temperatures that is included in the above ranges. Anysuitable psig steam 30 may be used. In embodiments, the steam 30 is 150psig or less. In an embodiment, the steam 30 is 50 psig. In anembodiment, the steam 30 is 150 psig.

With continued reference to FIG. 2, as the methylmorpholine-N-oxide 25reacts with and removes the sulfur contaminants in the gas layer 20, theconcentration gradient of the sulfur contaminants in the gas layer 20may decrease. Any sulfur contaminants that may have been present in thewater layer 15 may evaporate into the gas layer 20 after a heat transferinitiated by the application of the steam 30. The rate at which thesulfur contaminants evaporate into the gas layer 20 may be determined bythe temperature, pressure, and the concentration gradient of the sulfurcontaminants in the gas layer 20. The methylmorpholine-N-oxide 25 maythen act to remove the sulfur contaminants that have evaporated into thegas layer 20 from the water layer 15, thus decontaminating both the gaslayer 20 and the water layer 15. The rate of evaporation may be adjustedby increasing the temperature of the system, reducing the pressure ofthe system, increasing the surface area of the interface between thewater layer 15 and the gas layer 20, or any other suitable means forevaporating the sulfur contaminants into the water layer 15.

With reference to FIGS. 1 and 2, in optional embodiments, themethylmorpholine-N-oxide 25 may react with the sulfur contaminants inthe presence of iron oxide (e.g., rust). Without being limited bytheory, the presence of iron oxide catalyzes themethylmorpholine-N-oxide 25 to convert the sulfur contaminants toelemental sulfur and thiosulfate reaction products irreversibly. Anysuitable iron oxide may be used. In embodiments, the iron oxide includeshydrated iron oxide, anhydrous iron oxide, or any combinations thereof.In an embodiment, the iron oxide is hydrous iron oxide. In embodiments,the iron oxide includes ferrous or ferric oxides that are hydrated. Inan embodiment, the iron oxide is Fe₂O₃.7H₂O, Fe₂O₃.10H₂O, or anycombinations thereof. The iron oxide may be present in vessel 10 in anyamount suitable to catalyze the reaction between the amine oxide and thecontaminants. In an embodiment, vessel 10 has iron oxide in the waterlayer 15 in an amount from about 100 ppm iron oxide to about 1,000 ppmiron oxide. In embodiments, the iron oxide may be present in anyindividual amount in the above range or any smaller range of amountsthat is included in the above range. In embodiments, no iron oxide isadded to vessel 10 as methylmorpholine-N-oxide water treatment method 5uses the iron oxide already present in vessel 10. In other embodiments,iron oxide is added to vessel 10. Without limitation by theory, thereaction to remove the sulfur contaminants from the water layer 15 andthe gas layer 20 comprises methylmorpholine-N-oxide, steam, and ironoxide. The reaction may be allowed to occur for a sufficient time toallow the sulfur contaminants to be removed (i.e., converted) from thewater layer 15 and/or the gas layer 20. In embodiments, the reaction isallowed to occur from about one hour to about fifty hours, alternativelyfrom about one hour to about twenty-five hours. In embodiments, thereaction time may be any individual time in the above times or anysmaller time ranges that are included in the above ranges. FIG. 3illustrates examples of reaction time versus temperature. Withoutlimitation by theory, it is to be understood that the higher thetemperature, the less reaction time may be used. In embodiments, thereaction is allowed to occur for a sufficient time to substantiallyremove all of the sulfur contaminants (i.e., convert substantially allof the reactive sulfide to elemental sulfur). In some embodiments, thereaction produces substantially no foaming. And, in some embodiments,the reaction also may not generate ammonia. In an embodiment, thereaction is non-exothermic. In other embodiments, surfactants are notadded to the contaminated water or methylmorpholine-N-oxide 25. In someembodiments (e.g., the embodiment described by FIG. 1), if sufficientiron oxide is present, a suitable reaction time for an application maybe obtained without the use of steam 30. Thus, for some embodiments (notillustrated), steam is not added to vessel 10.

After the desired reaction time occurs (i.e., sulfide conversion isabout complete), the treated water 35 (i.e., treated water) may be drawnoff from vessel 10 and nonhazardous products 40 may also be removed fromvessel 10. Treated water 35 may be sent to any desired location such asa water treatment plant. In embodiments, treated water 35 has no sulfurcontaminants. Nonhazardous products 40 include nonhazardous sulfurreaction products along with other native solids in vessel 10 (i.e.,sludge). Nonhazardous products 40 may be removed from vessel 10 by anysuitable means. In an embodiment, the means include a centrifuge. Inembodiments, the liquid portion of the effluent passing from thecentrifuge may then be routed to a treatment facility or any otherdesirable location.

In the embodiments shown in FIGS. 1 and 2, methylmorpholine-N-oxidewater treatment method 5 may also include re-circulation 45.Re-circulation 45 is the re-circulation of the water layer 15. In someembodiments, water layer 15 containing methylmorpholine-N-oxide 25 isre-circulated. Without limitation, re-circulation 45 facilitatesdistribution of methylmorpholine-N-oxide 25 in the water layer 15. In anembodiment, from about one volume of the total amount of water layer 15in vessel 10 to about two volumes of the total amount of water layer 15in vessel 10 may be re-circulated. In embodiments, re-circulation 45 mayinclude re-circulation of any volume of water layer 15 or range ofvolumes less than two.

In embodiments as shown in FIG. 4, methylmorpholine-N-oxide watertreatment method 5 includes heat exchanger 50, which adds heat tore-circulation 45. Without limitation, adding the heat may increase thereaction rate.

To further illustrate various illustrative embodiments of the presentinvention, the following examples are provided.

EXAMPLES Example 1

A purpose of this Example was to determine the extent of the reaction ofmorpholine-N-oxide on a sulfur contaminant (i.e. H₂S) in water atvarying mole ratios. The experiments were conducted at 40° C. and 60° C.At all mole ratios (morpholine-N-oxide:H₂S) down to and including1.0:1.0, the destruction of H₂S was complete at 60° C. after 24 hours.Elemental sulfur was a visible product. This sulfur was present asplatelets (“flakes”). After 24 hours at 40° C., the reaction wascomplete only at a mole ratio of 3.0:1.0, although nearly completereactions were recorded at ratios of 2.0:1.0 and 1.8:1.0. Reactions atlower mole ratios were variously incomplete and consistent with thelower loadings. After 48 hours at 40° C., the reaction was complete atall mole ratios except for the lowest loading (1.0:1.0). The product wasvariously present as a milky suspension and flaked solids.

For the experiment, a pint of archived sour water at pH-8.5 was usedwith an H₂S content at 9,985 mg/liter (0.293 M/lit). The molecularweight of the solid methylmorpholine-N-oxide was 126.0. Amethylmorpholine-N-oxide stock solution was prepared by dissolving 5.00grams in 100.0 mLs distilled water (0.397 M/lit). To each of severalscrew-capped sample vials, 2.0 mLs of the sour water and a dash ofpowdered iron rust were added. The vials were then diluted with ˜15 mLsof distilled water and the following volumes of methylmorpholine-N-oxidewere added.

TABLE 1 Sample Makeup [Methylmorpholine-N-oxide] = 0.397 M/lit [H₂S] =0.293 M/lit (@ pH ~8.5) ~0.5 gm Fe₂O₃•xH₂O Volume Mole ratiomethylmorpholine- (Methylmorpholine- N-oxide stock N-oxide:H₂S) 1.477mLs 1.0:1 1.772 mLs 1.2:1 2.067 mLs 1.4:1 2.363 mLs 1.6:1 2.658 mLs1.8:1 2.953 mLs 2.0:1 4.430 mLs 3.0:1

Three such series were prepared. Each series was treated as follows:series 1: heated at 40° C. for 24 hours (static), series 2: heated at40° C. for 48 hours (static), series 3: heated at 60° C. for 24 hours(static). At termination of the reaction periods, the entire contents ofeach reaction vial were emptied into 20 mls of sulfide anti-oxidantbuffer, and each was titrated with 0.100 M/lit Pb⁺⁺. The results areshown below.

TABLE 2 Reaction of Morpholine-N-oxide on H₂S for 24 Hours @ 40° C. mlsGms H₂S Gms H₂S % Sample Pb⁺⁺ Titrated Added Reacted 1.0:1 1.9 0.000190.000585 68% 1.2:1 1.8 0.00018 0.000585 69% 1.4:1 1.7 0.00017 0.00058571% 1.6:1 0.7 0.00007 0.000585 88% 1.8:1 0.4 0.00004 0.000585 93% 2.0:10.3 0.00003 0.000585 95% 3.0:1 0.0 0.00000 0.000585 100% 

TABLE 3 Reaction of Morpholine-N-oxide on H₂S for 48 Hours @ 40° C. mlsGms H₂S Gms H₂S % Sample Pb⁺⁺ Titrated Added Reacted 1.0:1 0.4 0.000040.000585  93% 1.2:1 0.0 0.00000 0.000585 100% 1.4:1 0.0 0.00000 0.000585100% 1.6:1 0.0 0.00000 0.000585 100% 1.8:1 0.0 0.00000 0.000585 100%2.0:1 0.0 0.00000 0.000585 100% 3.0:1 0.0 0.00000 0.000585 100%

Elemental sulfur, present as small platelets, had been precipitatedduring reaction.

TABLE 4 Reaction of Morpholine-N-oxide on H₂S for 24 Hours @ 60° C. mlsGms H₂S Gms H₂S % Sample Pb⁺⁺ Titrated Added Reacted 1.0:1 0.0 0.000000.000585 100% 1.2:1 0.0 0.00000 0.000585 100% 1.4:1 0.0 0.00000 0.000585100% 1.6:1 0.0 0.00000 0.000585 100% 1.8:1 0.0 0.00000 0.000585 100%2.0:1 0.0 0.00000 0.000585 100% 3.0:1 0.0 0.00000 0.000585 100%

Elemental sulfur, present as small platelets, had been precipitatedduring reaction.

Example 2

A purpose of this example was to determine if a lower ratio than 1.0:1.0of methylmorpholine-N-oxide:sulfide will completely remove sulfide fromsolution. The experiments were conducted at 40° C. and 60° C. At a moleratio of 0.7:1.0 (methylmorpholine-N-oxide: H₂S), the oxidation andremoval of sulfide appeared to be 98%-99% complete.

A pint of archived sour water at pH˜8.5 was used that had an H₂S contentat 8,016 mg/liter (0.250 M/lit). A sample of solid4-methylmorpholine-N-oxide was determined to have a molecular weight of126.0. A 4-methylmorpholine-N-oxide stock solution was prepared bydissolving 5.00 grams in 100.0 mls distilled water (0.397 M/lit). Toeach of four screw-capped sample vials, 2.0 mls of the sour water and anamount of powdered iron rust were added. The vials were diluted to ˜20mls with distilled water after adding 0.822 mls of4-methylmorpholine-N-oxide, which amounted to a reaction ratio of0.7:1.0.

Two of the samples were placed in a 40° C. bath for a reaction time of48 hours. The other two were placed in a 60° C. bath for 24 hours. Attermination of the reaction periods, the entire contents of a reactionvial from each bath were emptied into 20 mls of sulfide anti-oxidantbuffer, and each was titrated with 0.100 M/lit Pb⁺⁺. The sample reactedat 40° C. required 0.10 mls of the Pb⁺⁺ titrant, and the sample reactedat 60° C. required 0.05 mls. These analysis results calculated to 99%and 98% destruction of sulfide in the tests.

The second samples from these reactions were acidified with H₂SO₄. Thiswas done in order to determine if there was any odor of residual H₂S.There was no odor of H₂S. Instead, there was the unmistakable odor ofSO₂. A common reaction product of N-oxides with sulfur is thiosulfate.When thiosulfate is acidified, it disproportionates, forming SO₂.Elemental sulfur, present as small platelets, had been formed duringboth reactions.

Example 3

A sample from a large sour water tank was tested.Methylmorpholine-N-oxide with added temperature of 50° C. was found toreduce hydrogen sulfide to 0 ppm in 19 hours or less. During the courseof the testing, discoveries were made about the catalytic effect of thevoluminous corrosion solids in the tank. When such solids were present,methylmorpholine-N-oxide trials at ambient temperatures were found to becomplete with hydrogen sulfide at 0 ppm after 24 hours treatment time.Other trials where the solids were removed prior tomethylmorpholine-N-oxide treatment demonstrated thatmethylmorpholine-N-oxide reduced hydrogen sulfide to 0 ppm in six daysat ambient conditions.

A sample of the tank was taken and found to be black from suspendedcorrosion solids (Fe₂O₃+FeS). Various analyses were conducted in orderto determine H₂S content so that a methylmorpholine-N-oxide dose couldbe calculated. Prior readings were 800-900 ppm H₂S. A test using aCHEMETS® sulfide colorimetric test kit estimated 400-500 ppm H₂S.Iodometric titration gave an H₂S result of 600-700 ppm on the wholesample, and 400-500 ppm H₂S on filtered sample.

The first demonstration was performed under standard conditions wheretreatments were assisted by heating at 50° C. Two different dosagelevels were prepared using newly-made as well as eight month oldformulation. One sample was run at ambient conditions. The test make-upsare below in Table 5.

TABLE 5 Reaction of Morpholine-N-oxide on H₂S for 19 Hours @ VaryingTemperatures First Tank methylmorpholine- Sample N-oxide:H₂S Temp (mL)mole ratio (° C.) 15 1.5:1  50 15 3:1 50 15 3:1 50 15 3:1 Ambient

After 19 hours under the test conditions described above, the heatedsamples were observed to be completely reacted (H₂S=0 ppm). Also, theambient sample was mostly reacted as evidenced by a cloudy yellowsolution, which is typical for that course of the reaction.

Verification of the completion of H₂S oxidation was seen in the leadacetate test strips. A dark strip was untreated, the clear stripincluded the three heated samples with H₂S=0 ppm, and another strip wasthe ambient sample that was seen to be much lighter. A subsequent testwith CHEMETS® colorimetric sulfide kit indicated the H₂S levels in theambient sample to be well below 100 ppm H₂S. These tests suggested thatthe presence of significant amounts of corrosion material were such asufficient catalyst for timely methylmorpholine-N-oxide reactions thatheat may not be a necessity in every application.

Lab trials were initiated to study the effectiveness ofmethylmorpholine-N-oxide at low dose rates and under ambient conditions.The sample array was intended to study the reaction rate ofmethylmorpholine-N-oxide with and without the iron oxide catalyticsolids and also varying dose rates. One sample represented the mostextreme test of methylmorpholine-N-oxide—ambient conditions with no ironoxide present and a methylmorpholine-N-oxide:H₂S ratio of 1:1 (i.e., thelowest theoretical dose rate possible). Test parameters were summarizedin Table 6.

TABLE 6 Reaction of Morpholine-N-oxide on H₂S for 24 Hours @ AmbientTemperatures Mole ratio methylmorpholine-N- oxide:H₂S Solids LevelTemperature  1:1 Minimal Ambient 1.5:1 Minimal Ambient 1.5:1 Abundant -Sx Shaken Ambient

After 24 hours of exposure, methylmorpholine-N-oxide was found toproduce complete eradication of H₂S in the sample with solids asevidenced. This was consistent with the ambient test with solids above.Also, the higher dose sample with no solids looked to be turning adarker shade of yellow, which indicated some initial progress inreaction.

Both of the samples with no solids present were also seen toprogressively react with all the H₂S as well, at much longer reactiontimes. A summary of the results is included in Table 7.

TABLE 7 Summary of H₂S Treatment Results Solids Mole Time to PresentRatio H₂S = 0 ppm Yes 1.5:1 24 hours No 1.5:1 6 days No  1:1 12 days(theoretical minimum)

Example 4

A sample was obtained comprising 9,066 ppm H₂S as measured using aCHEMETS® sulfide colorimetric test kit. Prior readings indicated thesample had a H₂S concentration greater than 12,000 ppm. A sample ofsolid 4-methylmorpholine-N-oxide was determined to have a molecularweight of 126.0. A 4-methylmorpholine-N-oxide stock solution wasprepared by dissolving 5.00 grams in 100.0 mls distilled water (0.397M/lit). The sample was distributed into three separate sample vialscomprising 20 mL of the original sample. To each of the three samplevials an amount of powdered iron rust was added.Methylmorpholine-N-oxide was added to the three vials in an amount of 2,2.5, and 3.8 mLs to provide a ratio of methylmorpholine-N-oxide:H₂S of1.5:1, 2:1, and 3:1 respectively. The three samples were placed in a 50°C. bath for a reaction time of 24 hours. The results are shown in Table8.

TABLE 8 Reaction of Morpholine-N-oxide on H₂S for 24 Hoursmethylmorpholine-N- oxide:H₂S Estimated Completed mole ratio ReactionTime 1.5:1  >32 2:1 26 3:1 <24

The 3:1 sample reached reaction completion at less than 24 hours. The2:1 sample reached reaction completion at 26 hours. The 1.5:1 sample hadnot reached reaction completion by 32 hours when the experiment wasstopped, however, the appearance of the vile indicated that some measureof the H₂S had been treated.

The preceding description provides various embodiments of the systemsand methods of use disclosed herein which may contain different methodsteps and alternative combinations of components. It should beunderstood that, although individual embodiments may be discussedherein, the present disclosure covers all combinations of the disclosedembodiments, including, without limitation, the different componentcombinations, method step combinations, and properties of the system. Itshould be understood that the compositions and methods are described interms of “comprising,” “containing,” or “including” various componentsor steps, the compositions and methods can also “consist essentially of”or “consist of” the various components and steps. Moreover, theindefinite articles “a” or “an,” as used in the claims, are definedherein to mean one or more than one of the element that it introduces.

For the sake of brevity, only certain ranges are explicitly disclosedherein. However, ranges from any lower limit may be combined with anyupper limit to recite a range not explicitly recited, as well as, rangesfrom any lower limit may be combined with any other lower limit torecite a range not explicitly recited, in the same way, ranges from anyupper limit may be combined with any other upper limit to recite a rangenot explicitly recited. Additionally, whenever a numerical range with alower limit and an upper limit is disclosed, any number and any includedrange falling within the range are specifically disclosed. Inparticular, every range of values (of the form, “from about a to aboutb,” or, equivalently, “from approximately a to b,” or, equivalently,“from approximately a-b”) disclosed herein is to be understood to setforth every number and range encompassed within the broader range ofvalues even if not explicitly recited. Thus, every point or individualvalue may serve as its own lower or upper limit combined with any otherpoint or individual value or any other lower or upper limit, to recite arange not explicitly recited.

Therefore, the present embodiments are well adapted to attain the endsand advantages mentioned as well as those that are inherent therein. Theparticular embodiments disclosed above are illustrative only, and may bemodified and practiced in different but equivalent manners apparent tothose skilled in the art having the benefit of the teachings herein.Although individual embodiments are discussed, the disclosure covers allcombinations of all of the embodiments. Furthermore, no limitations areintended to the details of construction or design herein shown, otherthan as described in the claims below. Also, the terms in the claimshave their plain, ordinary meaning unless otherwise explicitly andclearly defined by the patentee. It is therefore evident that theparticular illustrative embodiments disclosed above may be altered ormodified and all such variations are considered within the scope andspirit of those embodiments. If there is any conflict in the usages of aword or term in this specification and one or more patent(s) or otherdocuments that may be incorporated herein by reference, the definitionsthat are consistent with this specification should be adopted.

What is claimed is:
 1. A method for removing hydrogen sulfide,comprising: (A) introducing a methylmorpholine-N-oxide solution to avessel, wherein the vessel comprises a water layer and a gas layer,wherein the water layer and the gas layer comprise the hydrogen sulfide;(B) introducing methylmorpholine-N-oxide into the gas layer; wherein themethylmorpholine-N-oxide comprises between about 0.01 weight volume %and about 60 weight volume % methylmorpholine-N-oxide of the gas layer;(C) introducing steam to the vessel, wherein steam removes at least aportion of the hydrogen sulfide from the water layer; (D) allowing thesteam comprising at least a portion of hydrogen sulfide from the waterlayer to evaporate into the gas layer; (E) adjusting a hydrogen sulfiderate of evaporation by increasing the vessel temperature; (F) treatingthe gas layer by allowing the methylmorpholine-N-oxide to react with thehydrogen sulfide; and (G) treating the water layer by reducing thetemperature of the gas layer to a temperature below the boiling point ofmethylmorpholine-N-oxide to condense into the water layer.
 2. The methodof claim 1, further comprising allowing the hydrogen sulfide in thewater layer to react with the methylmorpholine-N-oxide.
 3. The method ofclaim 1, wherein the treating the water layer comprises converting thehydrogen sulfide to elemental sulfur.
 4. The method of claim 1, whereinthe elemental sulfur is removed from the vessel.
 5. The method of claim1, wherein the methylmorpholine-N-oxide solution is introduced to thegas layer in an amount to provide a mole ratio ofmethylmorpholine-N-oxide to hydrogen sulfide in the vessel from about1.0 mole methylmorpholine-N-oxide:1.0 mole hydrogen sulfide to aboutabout 3.0 moles methylmorpholine-N-oxide:1.0 mole hydrogen sulfide. 6.The method of claim 1, further comprising introducing the steam to thevessel to increase a temperature of the gas layer to a temperature fromabout 234° F. to about 250° F.
 7. The method of claim 1, furthercomprising recirculating between about one volume of the water layer inthe vessel to about two volumes of water layer in the in the vessel,wherein the recirculating further comprises heating the water layer. 8.The method of claim 1, wherein the water layer further comprises an ironoxide.
 9. A method for removing hydrogen sulfide, comprising: (A)introducing a methylmorpholine-N-oxide solution to a vessel, wherein thevessel comprises a water layer and a gas layer, wherein the water layerand the gas layer comprise the hydrogen sulfide; (B) introducingmethylmorpholine-N-oxide into the gas layer; wherein themethylmorpholine-N-oxide solution is introduced to the gas layer in anamount to provide a mole ratio of methylmorpholine-N-oxide to hydrogensulfide in the vessel from about 1.0 mole methylmorpholine-N-oxide:1.0mole hydrogen sulfide to about about 3.0 molesmethylmorpholine-N-oxide:1.0 mole hydrogen sulfide; (C) introducingsteam to the vessel, wherein steam removes at least a portion of thehydrogen sulfide from the water layer; (D) allowing the steam comprisingat least a portion of hydrogen sulfide from the water layer to evaporateinto the gas layer; (E) adjusting a hydrogen sulfide rate of evaporationby increasing the vessel temperature; (F) treating the gas layer byallowing the methylmorpholine-N-oxide to react with the hydrogensulfide; and (G) treating the water layer by reducing the temperature ofthe gas layer to a temperature below the boiling point ofmethylmorpholine-N-oxide to condense into the water layer.
 10. Themethod of claim 9, further comprising allowing the hydrogen sulfide inthe water layer to react with the methylmorpholine-N-oxide.
 11. Themethod of claim 9, wherein the treating the water layer comprisesconverting the hydrogen sulfide to elemental sulfur.
 12. The method ofclaim 9, wherein the elemental sulfur is removed from the vessel. 13.The method of claim 9, further comprising introducing the steam to thevessel to increase a temperature of the gas layer to a temperature fromabout 234° F. to about 250° F.
 14. The method of claim 9, furthercomprising recirculating between about one volume of the water layer inthe vessel to about two volumes of water layer in the in the vessel,wherein the recirculating further comprises heating the water layer. 15.The method of claim 9, wherein the water layer further comprises an ironoxide.
 16. A method for removing hydrogen sulfide, comprising: (A)introducing a methylmorpholine-N-oxide solution to a vessel, wherein thevessel comprises a water layer and a gas layer, wherein the water layerand the gas layer comprise the hydrogen sulfide, wherein the water layerfurther comprises and iron oxide; (B) introducingmethylmorpholine-N-oxide into the gas layer; (C) introducing steam tothe vessel, wherein steam removes at least a portion of the hydrogensulfide from the water layer; (D) allowing the steam comprising at leasta portion of hydrogen sulfide from the water layer to evaporate into thegas layer; (E) adjusting a hydrogen sulfide rate of evaporation byincreasing the vessel temperature; (F) treating the gas layer byallowing the methylmorpholine-N-oxide to react with the hydrogensulfide; and (G) treating the water layer by reducing the temperature ofthe gas layer to a temperature below the boiling point ofmethylmorpholine-N-oxide to condense into the water layer.
 17. Themethod of claim 16, wherein the iron oxide acts as a catalyst in areaction between the methylmorpholine-N-oxide and the hydrogen sulfide.18. The method of claim 16, wherein the water layer comprises from about100 ppm iron oxide to about 1,000 ppm iron oxide.
 19. The method ofclaim 16, wherein the treating the water layer comprises converting thehydrogen sulfide to elemental sulfur.
 20. The method of claim 16,further comprising recirculating between about one volume of the waterlayer in the vessel to about two volumes of water layer in the in thevessel, wherein the recirculating further comprises heating the waterlayer.